If Ubuntu offers binary packages for aarch64 like i386/amd64, please try this:
*) Run command "uname -m" on your aarch64 server. Copy its output string.
*) Open file 'conf/global' in iRedMail-0.9.7 (or iRedMail-0.9.8-beta1), find lines below:
# Check hardware architecture.
arch="$(uname -m)"
case $arch in
i[3456]86) export OS_ARCH='i386' ;;
x86_64|amd64) export OS_ARCH='x86_64' ;;
armv6l|arm7l|armv7l)
# Debian ARM platform and Raspberry Pi.
export OS_ARCH='armhf' ;;
*)
echo "Your architecture is not supported yet: ${arch}."
echo "Both i386 and x86_64 are supported by ${PROG_NAME}."
exit 255
;;
esac
*) Now add one more switch for the output command "uname -m" in step 1, like below:
# Check hardware architecture.
arch="$(uname -m)"
case $arch in
i[3456]86) export OS_ARCH='i386' ;;
x86_64|amd64) export OS_ARCH='x86_64' ;;
armv6l|arm7l|armv7l)
# Debian ARM platform and Raspberry Pi.
export OS_ARCH='armhf' ;;
aarch64)
export OS_ARCH='aarch64' ;;
*)
echo "Your architecture is not supported yet: ${arch}."
echo "Both i386 and x86_64 are supported by ${PROG_NAME}."
exit 255
;;
esac
Now run iRedMail installer. Show me the output if there's any error.